Dr. Demetria “Demi” Cronin Moon, age 51, passed away peacefully on Sunday, May 31, 2026, at Avera McKennan Hospital in Sioux Falls, South Dakota, after a courageous battle with Acute Myeloid Leukemia. She leaves behind a legacy of love, learning, and leadership that will endure in the lives of everyone she touched.

A memorial visitation will be held on Thursday, June 11, 2026 at George Boom Funeral Home & On-Site Crematory in Sioux Falls beginning at 4:00 p.m. followed by a liturgical wake service at 7:00 p.m.

Her memorial Mass of Christian burial will be 11:00 a.m., on Friday, June 12, 2026 at Holy Trinity Catholic Parish in Huron, SD with burial to follow at St. Martin Catholic Cemetery.

Demi was born on October 28, 1974, at the Portsmouth, Virginia Naval Hospital to Dennis Dean and Kathryn (DuBose) Cronin. She was raised in Huron, South Dakota, where she developed the ambition and integrity that would greatly influence her life. Demi graduated from Huron High School in 1993 and earned her Bachelor's degree in Mathematics from South Dakota State University in 1997. Over the next twenty-six years, she would go on to earn a Master’s Degree in Curriculum & Instruction from Black Hills State University; a School District Superintendent Education Specialist Degree; and an Education Leadership Doctoral Degree from the University of South Dakota. Education was not simply her profession; it was her calling.

While attending South Dakota State University, Demi met fellow resident advisor Daniel Nathan Moon. They were united in marriage on August 8, 1998, at St. Martin Catholic Church in Huron and built a life centered on faith and family. Together, they raised four children: Cassidy, Nathan, Lillian, and Sophia.

Demi began her teaching career in 1997 in Arlington, South Dakota. In 2000, she returned to Huron High School to teach mathematics. As a teacher, she was known for her exceptional commitment to students and colleagues. Her excellence in the classroom helped earn her positions of Assistant Principal and Principal at Huron High School. In her time at Huron High School, Demi was awarded Teacher of the Year and SD Assistant Principal of the Year. Her rise through the field of education was a reflection not of ambition, but of the profound respect and trust she inspired in those around her.

In 2016, the Moon family relocated to Sioux Falls, where Demi joined the Sioux Falls School District. She served in various districtwide administrative roles before becoming Principal at Memorial Middle School. In every role, she brought the same fierce commitment to her students, to her staff, and to every family who walked through the doors of her school. She had a particular gift for mentoring young educators, seeing in them the same potential she had once been given the chance to develop.

Beyond her remarkable career, Demi’s greatest joy was her family. She was a devoted wife and mother - selfless, inspirational, and endlessly loving. Her role as a gymnastics and hockey mom found her cheering from the bleachers in gyms and hockey rinks across the country. Her love showed up in countless ways, in the traditions that made holidays special, and in the adventures she planned to give her children a lifetime of memories. She opened the doors of her home to multiple “billet” sons, who all loved her dearly. Demi had a gift for making every child feel welcomed and cherished. She was not just a mother to four, she was a second mother to many. Demi was eagerly awaiting the arrival of her first grandchild this summer, a joy she held close to her heart.

Demi is survived by her beloved husband, Daniel Moon of Sioux Falls, SD; her four children, Cassidy (Nolan) Walker, Nathan (Miah) Moon, Lillian Moon, and Sophia Moon, all of Sioux Falls; her mother, Kathryn (Marshall) Limpic of Kansas City, MO; step-mother, Mary (Roy) Mehling of Wessington, SD; Daniel’s parents, George and Marsha Moon of Omaha, NE; brother, Tony (Kristin) Cronin of Huron, SD; half-sister, Kelly Cronin of Huron, SD; step-siblings, Ryan (Megan) Myers and Vanessa (Bob) Perrenoud of Huron, SD; Daniel’s siblings, Nickie (Wade) Landis and Kevin (Sabra) Moon, both of Omaha, NE; and a cherished community of extended family and dear friends.

She was preceded in death by her father, Dennis Dean Cronin.

In lieu of flowers, memorials may be directed to the Dr. Demi Moon Memorial Scholarship at the Huron Area Education Federal Credit Union (1855 Arizona Avenue SW Huron, SD 57350), or to Blood Cancer United. These organizations reflect two causes that heavily impacted her life: supporting students through education and advancing the fight against the disease that took her far too soon.

Though her time here was shortened, Demi’s impact was immeasurable. She taught others to lead with kindness, serve with purpose, and love without reservation. Her memory will live on in the students she inspired, the educators she mentored, the friends she cherished, and most of all, the family she loved beyond measure.